KR101267531B1 - Method of rubbing base substrate for liquid crystal display device - Google Patents

Abstract

A rubbing method for a base substrate for a liquid crystal display device comprising an alignment layer, the method comprising: forming a cell on which a process key is formed at each of four corners thereof; Measuring a degree of twist of the cell with respect to the base substrate through coordinate measurement using the process key; A rubbing method of a base substrate for a liquid crystal display device, the method comprising: rubbing the cell using a rubbing device whose axial direction is parallel to the edge of the cell, adjusted according to the degree of distortion of the cell.

Description

Rubbing method of base substrate for liquid crystal display device {METHOD OF RUBBING BASE SUBSTRATE FOR LIQUID CRYSTAL DISPLAY DEVICE}

1 is a schematic plan view of a rubbing process of a substrate for a transverse electric field mode liquid crystal display according to the related art.

2A, 2B and 2C are plan views illustrating a rubbing method of a substrate for a transverse electric field mode liquid crystal display according to an exemplary embodiment of the present invention in a process sequence.

3 is a plan view illustrating a rubbing process of a substrate for a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a cross-sectional view of one pixel portion of a transverse electric field type liquid crystal display device according to an exemplary embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

210: base substrate 230: cell

240: process key 280: rubbing device

RA: rubbing axis θ1, θ2: first, second angle

The present invention relates to a rubbing method of a substrate, and more particularly to a rubbing method of a substrate for a liquid crystal display device.

Generally, the driving principle of a liquid crystal display device utilizes the optical anisotropy and polarization properties of a liquid crystal. Since the liquid crystal has a long structure, it has a directionality in the arrangement of molecules, and the direction of the molecular arrangement can be controlled by artificially applying an electric field to the liquid crystal.

Accordingly, if the molecular arrangement direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and light is refracted in the molecular arrangement direction of the liquid crystal by optical anisotropy to express an image.

In general, a liquid crystal display device includes two substrates disposed to face each other, and a liquid crystal layer interposed between the two substrates, and a vertical electric field formed between two electrodes by forming electrodes on inner surfaces of the two substrates facing each other. The method of driving the liquid crystal layer is a twist nematic mode liquid crystal display device, and the method of driving the liquid crystal layer by a transverse electric field between two electrodes by arranging two electrodes alternately on one electrode is a transverse electric field mode. (in-plane switching mode) Can be defined as a liquid crystal display device. Among them, the transverse electric field mode liquid crystal display device is used in the viewing angle characteristic improvement mode because it is driven by the horizontal electric field.

Referring to the manufacturing process of a general liquid crystal display device, an array element including a thin film transistor is formed on a first substrate, and a color filter element including a black matrix and a color filter is formed on a second substrate. The liquid crystal layer is interposed between the two substrates, including a process of coating and rubbing an alignment layer on an inner surface which is in contact with the liquid crystal layer.

The rubbing is a main process of determining the initial alignment direction of the liquid crystal. The rubbing of the alignment layer enables the normal liquid crystal to be driven and has a uniform display characteristic. In general, the alignment layer is mainly a polyimide series, which is an organic alignment layer, and the rubbing process refers to rubbing the alignment layer in a predetermined direction using a cloth, and the liquid crystal molecules are aligned according to the rubbing direction.

For example, in the case of the twisted nematic mode liquid crystal display, rubbing is performed at an angle of 45 degrees with respect to the substrate, whereas in the case of the transverse electric field mode liquid crystal display, rubbing is performed with a 0 degree inclination parallel to the substrate. .

1 is a schematic plan view of a rubbing process of a substrate for a transverse electric field mode liquid crystal display according to the related art.

As shown in the drawing, a cell 12 for a liquid crystal display device is formed in the base substrate 10. Although not shown in the drawings, the cell 12 may be an array cell including a thin film transistor or a color filter cell including a color filter. In the case of a transverse electric field mode liquid crystal display, since both the pixel electrode and the common electrode are formed on one substrate, if the cell 12 is an array cell, a pixel electrode connected to the thin film transistor and a common electrode forming a transverse electric field with the pixel electrode It will include more.

Conventionally, before the rubbing process, the rubbing axis RA direction of the rubbing device 14 is parallel to the short axis of the substrate. However, patterns such as thin film transistors and color filters formed in the actual cell are rotated left, right or rotated. As it is formed, it may be distorted with a specific angle θ even with respect to the substrate. If the pattern of the cells 12 is misaligned with respect to the base substrate 10, there is a problem in that the contrast characteristics of the transverse electric field mode liquid crystal display device are significantly reduced.

More specifically, the above-described contrast is calculated by dividing the white luminance by the black luminance. In the transverse electric field mode, even if the rubbing direction changes only 0.1 degrees from the initially set 0 degree, the black luminance is increased. Therefore, there is a problem that the contrast characteristic is reduced that much.

Particularly, when the high definition characteristics are gradually connected to the product competitiveness and the user demand thereof is gradually increased, even in the case of twisted nematic liquid crystal display devices, it is difficult to have desired image quality characteristics according to the conventional rubbing method.

In order to solve the above problems, it is an object of the present invention to provide a rubbing method of a substrate for a liquid crystal display device that can improve the image quality characteristics including contrast characteristics by performing a rubbing process in the direction of the first designed rubbing axis.

In other words, the direction of rubbing axis is not set based on the base substrate during the rubbing process, and the rubbing axis direction is measured based on the distortion of the cell pattern by using a process key formed in the cell pattern in the base substrate. We want to set

In order to achieve the above object, according to a first aspect of the present invention, in a rubbing method of a base substrate for a liquid crystal display device including an alignment layer, forming a cell on which the process keys are formed at four corners, respectively, on the base substrate. Wow; Measuring a degree of twist of the cell with respect to the base substrate through coordinate measurement using the process key; A rubbing method of a base substrate for a liquid crystal display device, the method comprising: rubbing the cell using a rubbing device whose axial direction is parallel to the edge of the cell, adjusted according to the degree of distortion of the cell.

The rubbing device is characterized by consisting of a rubbing cloth wound around a rotating roller, the cell is characterized in that the array cell including a plurality of gate wiring and data wiring, a thin film transistor and a pixel electrode, the process key is the gate It is formed in the same process as the wiring, and the cell further comprises a common electrode for forming a transverse electric field with the pixel electrode.

The liquid crystal cell may be a color filter cell including a black matrix and a color filter, and the process key may be formed in the same process as the black matrix.

According to a second aspect of the present invention, there is provided a method comprising: forming first and second cells each having four process keys formed at four corners thereof on a first base and a second base substrate; Measuring a degree of distortion of the first and second liquid crystal cells with respect to the first and second base substrates through coordinate measurement using the process key; Rubbing the first and second cells, respectively, using a rubbing device adjusted in accordance with the degree of distortion of the first and second liquid crystal cells and having an axial direction parallel to a cell edge; Bonding the first and second base substrates so that the first and second liquid crystal cells face each other; Cutting the bonded first and second liquid crystal cells from the first and second base substrates, respectively; It provides a method for producing a liquid crystal cell comprising the step of forming a liquid crystal layer between the first and second liquid crystal cells.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

2A, 2B and 2C are plan views illustrating a rubbing method of a substrate for a transverse electric field mode liquid crystal display according to an exemplary embodiment of the present invention, according to a process sequence. For example, the case of manufacturing two cells on one base substrate is taken as an example.

In FIG. 2A, first and second base substrates 100 and 130 are provided, and a first cell 150 and a second cell 160 are formed in each of the first and second base substrates 100 and 130, respectively. have. Although not shown in detail in the drawings, each of the first cells 150 includes a plurality of gate lines and data lines arranged to cross each other, and a thin film transistor is formed at a point where the gate lines and data lines cross each other. The pixel electrode is connected to the pixel electrode, and the common electrode is formed to be spaced apart from the pixel electrode by a predetermined distance. In each of the second cells 160, a black matrix is formed in a non-pixel region, and a color filter is formed using the black matrix as a boundary for each color. In addition, an upper surface of each of the first and second cells 150 and 160 is coated with an alignment layer.

In FIG. 2B, first and second base substrates 110 and 130 including the first and second cells 150 and 160 are respectively mounted on an upper portion of a stage (not shown), and then the first and second base substrates 110 are disposed. And 130) rubbing the upper surfaces of the upper surfaces with the rubbing device 180.

For example, the rubbing device 180 is characterized in that consisting of a rubbing cloth wound on a rotating roller.

Referring to FIG. 3 in more detail in connection with features of the present invention, as shown, the cell 230 of the base substrate 210 according to the present invention includes a process key 240.

When forming the bottom layer pattern of the cell 230, the process key 240 may be formed in a cross shape at four corners of the outermost part of the cell 230 area. For example, in the case of an array cell, the gate wiring In the forming step, in the case of the color filter cell may be formed in the step of forming a black matrix. The process key 240 is used in a scribing process or an auto probe (AP) test.

That is, in the present invention, when setting the rubbing axis RA of the rubbing device 280, it is not based on the shortening of the substrate, but at the first angle θ1 through coordinate checking using the process key 240. After checking the degree of the pattern is twisted, the rubbing axis is rotated by a corresponding second angle θ2 as the pattern is twisted. In other words, the rubbing axis RA direction is adjusted parallel to the cell edge.

After setting the rubbing axis RA, rubbing may be performed by moving a stage (not shown), or rubbing may be performed by moving the rubbing device 280 on a fixed substrate.

Although not shown in the drawings, the four corners of the cell 230 may include an align key inwardly from the process key 240. For example, the process key 240 may be used to approximate an alignment key. The alignment key may be used to confirm the position and then increase the precision. It is important to note that in the rubbing process according to the present invention, in setting the axial direction of the rubbing device 280, the process key 240 formed in the cell 230 becomes a reference.

In addition, although the process key 240 having a cross shape is presented in the drawing, other shapes of the process key 240 may be applied as long as it is in accordance with the spirit of the present invention.

In FIG. 2C, the rubbing direction between the two substrates is obtained by combining the two substrates and then scribing and scribing the cells to form one liquid crystal panel LP. This allows for a more accurate value at the desired angle. Therefore, since it can have a desired pretilt angle in actual liquid crystal driving, it is possible to have a desired image quality characteristics.

4 is a cross-sectional view of one pixel part of a transverse electric field type liquid crystal display device according to an exemplary embodiment of the present invention.

As illustrated, the first and second substrates 310 and 330 are disposed to face each other, and the gate electrode 312, the semiconductor layer 314, the source electrode 316, and the inner surface of the first substrate 310 are disposed. A thin film transistor T formed of the drain electrode 318 is formed, and a protective layer 322 having a drain contact hole 320 partially exposing the drain electrode 318 is formed in a region covering the thin film transistor T. The pixel electrode 324 is formed on the passivation layer 322 by being connected to the drain electrode 318 through the drain contact hole 320. The common electrode 326 is formed to be spaced apart from the pixel electrode 324 by a predetermined distance, and the plurality of pixel electrodes 324 and the common electrode 326 are alternately disposed.

A first alignment layer 328 is formed in an area covering the pixel electrode 324 and the common electrode 326.

The black matrix 332 is formed in an area corresponding to the thin film transistor T and the gate line and data line not shown on the inner surface of the second substrate 330, and the color of each pixel area is formed on the black matrix 332. The filter layer 334 is formed, and the second alignment layer 336 is formed in the region covering the color filter layer 334. The liquid crystal layer 350 is interposed between the first and second alignment layers 328 and 336.

In the drawing, when the voltage is applied, the liquid crystal molecules of the liquid crystal layer 350 are horizontally arranged by a horizontal electric field formed between the pixel electrode 324 and the common electrode 326. The two alignment layers 328 and 336 are characterized by being subjected to an alignment process through a rubbing process.

Although not shown in the drawings, the rubbing method according to the present invention may be applied to a manufacturing method of a general twist nematic mode liquid crystal display device.

However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

As described above, according to the rubbing method of the substrate for a liquid crystal display according to the present invention, the rubbing direction is determined during the rubbing process by measuring the degree of distortion of the patterns formed in the cells in the base substrate using an alignment key. In addition, since the rubbing angle designed for the first time can be accurately realized, the image quality can be effectively improved when applied to a product having low contrast characteristics even in the case of minute distortion, such as a transverse electric field mode liquid crystal display.

Claims (8)

In the rubbing method of the base substrate for liquid crystal display devices containing an alignment film, Forming a cell on which the process key is formed at each of four corners of the base substrate; Measuring a degree of twist of the cell with respect to the base substrate through coordinate measurement using the process key; Rubbing the cell using a rubbing device adjusted in accordance with the degree of distortion of the cell and having an axial direction parallel to the edge of the cell Including, The cell is an array cell including a plurality of gate wirings and data wirings, a thin film transistor and a pixel electrode, and the process key is formed in the same process as the gate wiring which is the bottom layer of the cell. The rubbing method of the base substrate for apparatuses. The method of claim 1, And said rubbing device comprises a rubbing cloth wound around a rotating roller. delete delete The method of claim 1, And said cell further comprises a common electrode forming a transverse electric field with said pixel electrode. In the rubbing method of the base substrate for liquid crystal display devices containing an alignment film, Forming a cell on which the process key is formed at each of four corners of the base substrate; Measuring a degree of twist of the cell with respect to the base substrate through coordinate measurement using the process key; Rubbing the cell using a rubbing device adjusted in accordance with the degree of distortion of the cell and having an axial direction parallel to the edge of the cell Including, And said cell is a color filter cell comprising a black matrix and a color filter, and said process key is formed in the same process as said black matrix. The method of claim 6, And said rubbing device comprises a rubbing cloth wound around a rotating roller. Forming first and second cells on each of the first and second base substrates, each having a process key formed at four corners thereof; Measuring a degree of distortion of the first and second cells with respect to the first and second base substrates through coordinate measurement using the process key; Rubbing the first and second cells, respectively, using a rubbing device adjusted in accordance with the degree of distortion of the first and second cells and having an axial direction parallel to the edge of the cell; Bonding the first and second base substrates so that the first and second cells face each other; Cutting the joined first and second cells from the first and second base substrates, respectively; Forming a liquid crystal layer between the first and second cells Including, One of the first and second cells is a color filter cell including a black matrix and a color filter, and the process key is formed in the same process as the black matrix.

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